The present invention relates generally to medical implantable devices. More particularly, the invention relates to implantable medical devices that are able to communicate device identification parameters and information, as well as patient information, even when the implanted medical device has a depleted power source.
Implantable medical devices are used to treat patients suffering from various ailments. Some of the more common forms of implantable medical devices are implantable neurological stimulation devices, pacemakers, defibrillators and implantable drug delivery systems. For example, implanted neurological stimulator devices are used to treat patients suffering from such ailments as chronic pain, movement disorders, and incontinence.
A pacemaker is generally used to properly stimulate the heart when the body""s natural pacemaker malfunctions, due to age or disease. The pacemaker will deliver electrical pulses to an electrode that is implanted adjacent the patient""s heart in order to stimulate the heart so that it will beat at a desired rate.
Implantable defibrillators are used with patients prone to ventricular fibrillation. The implantable defibrillator senses physiological parameters and determines when to supply a defibrillating shock to a patient""s heart in an effort to overwhelm the unusual contractions of individual tissue sections and to restore the synchronized contraction of the total mass of heart tissue.
Implantable drug delivery systems provide stored drugs to target sites of patients. Implantable drug delivery systems usually rely upon physiological parameter sensors to provide signals that may be processed internally in order to determine when, and in what amount to deliver a drug dosage.
There are a myriad of other implantable medical devices available to patients today. The aforementioned devices are merely some of the more common devices in the medical field.
Existing implantable medical devices typically include a controller with memory, two way-communication capability, electrical circuitry and components, a therapy program, and an internal power source. The internal power source can be either a rechargeable or a non-rechargeable power source. Existing implantable medical devices typically have the ability to gather and process data relating to the patient""s physiological parameters. In this manner, the implanted medical device can determine when and what actions to take to address the needs of the patient. Existing implantable medical devices typically have two-way communications, such as a telemetry communication link, to communicate the gathered and stored data to the outside world. In this manner, patient information can be retrieved from the implanted medical device thereby allowing medical personnel to evaluate information relating to the status of a patient. Additionally, information relating to the identification and status of the implantable device itself can be retrieved from the implantable device. The two-way communication also allows medical personnel to transmit or deliver updated operating instructions to the implantable medical device to address any possible problems indicated by the retrieved physiological parameters or update the device parameters. Therefore, the ability to communicate with the implantable medical devices and extract or retrieve information, both device specific information and patient physiological information, is crucial in determining the appropriate treatment of the patient.
Existing implanted medical devices, as just described above, generally have a single power source. A drawback of existing implantable medical devices is that all external communication is lost when the single power source of the device is depleted. When the power source of the device is depleted, medical personnel are unable to communicate with the device. Under the circumstances in which these devices are used, it is important that some external communication be maintained and/or reestablished with the device to determine the physiological condition of the patient for appropriate patient diagnosis and treatment. Additionally, existing devices do not have the ability to communicate device identification and device information to the outside world once the power source is depleted.
Medical personnel need to have the ability to identify what type of device is in use before taking any action and administering any form of treatment to the patient. For example, some devices use a rechargeable main power source while others use a non-rechargeable main power sources. As such, there is a need to know, prior to administering medical assistance, what type of device is involved. Presently, this situation requires that patient files be located, X-rays taken to identify the implanted medical device, or in a worst case, that the device be removed for identification prior to rendering medical attention to the patient. Otherwise, incorrect medical assistance may result since it is unknown exactly what type of device is implanted in the patient if medical records are unavailable. This process takes time, which depending on the situation, may not be available due to the patient""s condition.
Other implantable medical devices use both rechargeable and non-rechargeable power sources simultaneously. In these types of devices, the non-rechargeable part of the power source is used to power the controller operating the implanted device since the power consumption of the controller is minimal, thereby allowing the controller to operate for a long period of time. In these types of devices, the rechargeable power source is used as the power source for the electrical stimulating pulses that are applied to the patient, since the pulses require more power than the controller. Feeding the electrical stimulating pulses from a separate rechargeable power source gives the implantable medical device a longer operating life. The timing, power and duration of the therapy pulses is controlled by the controller. However, when the non-rechargeable power source feeding the controller is depleted, there exists the same problem as described above, i.e., external communication with the implantable medical device is lost with no immediate way of identifying the implanted device or the condition of the patient from the implanted device.
Still other types of devices attempt to avoid the problem just described by avoiding a depleted power state altogether. These devices may employ design circuitry that will allow the implantable medical device to communicate a warning signal to the patient or medical personnel that a low critical power level is being approached so that precautionary steps may be taken. However, these devices too, lose the ability to communicate externally when power is depleted.
Thus, conventional implantable medical devices do not provide an apparatus or method to immediately energize a controller and retrieve device information and identification from an implantable medical device with a depleted power source.
The present invention provides an apparatus and method that allows external communication for positive device identification and for retrieval of device and patient information from an implantable medical device with a depleted primary or main power source. The apparatus and method of the present invention will allow an external programmer to immediately re-energize, within milli or micro seconds, the implantable medical device and subsequently retrieve device and patient information.
In accordance with the present invention, should the primary or main power source of an implantable medical device become depleted, an external programmer can deliver energy to a secondary or supplemental power source in the implantable medical device using telemetry, and preferably radio frequency (xe2x80x9cRFxe2x80x9d) telemetry. The energy transmitted via telemetry is sufficient to charge up the secondary or supplemental power source comprised of either a small capacitor, a rechargeable battery or other rechargeable energy storage device. Once the secondary power source is sufficiently charged, the secondary power source can be used to power up internal circuitry and a controller in the implantable medical device.
Once the internal circuitry and controller are operational, the implanted device can transmit information back to the external programmer via telemetry, including model identification information, type of primary or main power source used, patient information or any other desired information. The implantable medical device can then power down, since the secondary or supplemental power source is preferably large enough to allow the controller to temporarily operate and then transmit patient and device information to medical personnel. Use of the supplemental power source is preferably needed when the primary or main power source is depleted and retrieval of information is required prior to rendering medical attention or assistance. Otherwise the implantable medical device normally operates from the primary or main power source of the implantable medical device.
The present invention is viable whether the medical device uses a rechargeable or nonrechargeable battery as its primary or main power source. This is especially beneficial when the course of medical action to be taken depends on whether the power source is of the rechargeable or non-rechargeable type. If, for example, the medical device has a rechargeable power source, then the present invention will immediately identify it as such, and the rechargeable power source can be recharged. On the other hand, if the device is identified as being of the non-rechargeable variety, then recharging would not be an option and an alternate course of action can be taken. Without the present invention, the identification of the implantable medical device can take a longer period time and/or result in confusion or mistake as to what type of power source is being used.
Thus, it is an object of the present invention to provide an apparatus and method for the immediate reenergization of an implantable medical device having a depleted main power source and for the retrieval of device identification, device information and patient information, and further to do so within a short period of time, i.e., milli or micro seconds.
It is also an object of the present invention to provide an apparatus to allow for the retrieval of device identification, device information and patient information from an implantable medical device having either a depleted rechargeable or depleted non-rechargeable main power source.
It is a further object of the present invention to provide an apparatus to allow for the retrieval of device identification device, information and patient information from an implantable medical device having a depleted main power source through the use of telemetry communication.
It is a further object of the present invention to provide an apparatus to allow for the immediate retrieval of device identification, device information and patient information from an implantable medical device having a depleted main power source through the use of an RF external programmer.
It is also a further object of the present invention to provide an apparatus that will allow for the storage of energy that is transmitted via electromagnetic waves, such as in RF signals. In accordance with the present invention, the energy in the RF signals is stored in an energy storage component or device, or supplemental power source. In this manner the energy storage device or supplemental power source will be able to temporarily provide electrical power to the electrical and electronic components of the implantable medical device. In this manner, the temporarily powered medical device can communicate gathered and stored data to the outside world or receive information from the outside world via telemetry, e.g., RF signals.
It is also a further object of the present invention to provide a method for the storage of energy that is transmitted via electromagnetic waves, such as RF signals. In accordance with the present invention, energy transmitted via the RF signals is stored in an energy storage component or device. The energy storage device will then be able to temporarily provide power to the electrical and electronic components when the main power source is depleted. Information relating to the medical device can then be retrieved from, or delivered to the device via RF signals.